As we study classical mechanics, we see that velocity is a quantity relativeas it depends on the frame of reference in which it is measured.

This leads us to infer that other velocity-dependent quantities must also be relative, such as kinetic energy and the amount of motion, for example.

Gravitational potential energy is also a relative quantity, as its value depends on the reference level adopted to measure heights.

Already length, time and pasta are quantities that have always been treated as absolute. This means that the value of these quantities does not depend on the benchmark in which they are measured.

Later, we will see that such quantities can also be relative when the speed of the movements in which they are involved is very high, that is, not negligible compared to the speed of light (c = 300000 km / s).